J/A+A/621/A107 MUSE-Wide Lyman alpha luminosity function 3<z<6 (Herenz+, 2019)
The MUSE-Wide Survey: A determination of the Lyman α emitter luminosity
function at 3<z<6.
Herenz E.C., Wisotzki L., Saust R., Kerutt J., Urrutia T., Diener C.,
Schmidt K.B., Marino R.A., de la Vieuville G., Boogaard L., Schaye J.,
Guiderdoni B., Richard J., Bacon R.
<Astron. Astrophys. 621, A107 (2019)>
=2019A&A...621A.107H 2019A&A...621A.107H (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Galaxy catalogs
Keywords: cosmology: observations - galaxies: high-redshift -
galaxies: luminosity function - mass function -
techniques: imaging spectroscopy
Abstract:
We investigate the Lymanα emitter (LAE) luminosity function (LF)
within the redshift range 2.9≤z≤6 from the first instalment of the
blind integral field spectroscopic MUSE-Wide survey. This initial part
of the survey probes a region of 22.2arcmin2 in the CANDELS/GOODS-S
field (24 MUSE pointings with 1h integrations). The dataset provided
us with 237 LAEs from which we construct the LAE LF in the luminosity
range 42.2≤logLLyα[erg/s]≤43.5 within a volume of
2.3x105Mpc3. For the LF construction we utilise three different
non-parametric estimators: the classical 1/Vmax method, the C-
method, and an improved binned estimator for the differential LF. All
three methods deliver consistent results, with the cumulative LAE LF
being Φ(logLLyα[erg/s]=43.5)~=3x10-6Mpc-3 and
Φ(logLLyα[erg/s]=42.2)~=2x10-3Mpc-3 towards the bright
and faint end of our survey, respectively. By employing a
non-parametric statistical test, and by comparing the full sample to
subsamples in redshift bins, we find no supporting evidence for an
evolving LAE LF over the probed redshift and luminosity range. Using a
parametric maximum-likelihood technique we determine the best-fitting
Schechter function parameters α=-1.84+0.42-0.41 and
logL*[erg/s]=42.2+0.22-0.16 with the corresponding normalisation
logφ*[Mpc-3]=-2.71. However, the dynamic range in Lyα
luminosities probed by MUSE-Wide leads to a strong degeneracy between
α and L*. Moreover, we find that a power-law parametrisation
of the LF appears to be less consistent with the data compared to the
Schechter function, even so when not excluding the X-Ray identified
AGN from the sample. When correcting for completeness in the LAE LF
determinations, we take into account that LAEs exhibit diffuse
extended low surface brightness halos. We compare the resulting LF to
one obtained by applying a correction assuming compact point-like
emission. We find that the standard correction underestimates the LAE
LF at the faint end of our survey by a factor of 2.5. Contrasting our
results to the literature we find that at logLLyα[erg/s]~<42.5
previous LAE LF determinations from narrow-band surveys appear to be
affected by a similar bias.
Description:
This data release consists of the Lyman alpha emitter galaxy catalogue
and the selection functions used in the calculation of the Lyman alpha
luminosity function from the first instalment from the MUSE-Wide
survey (Herenz et al. 2017A&A...606A..12H 2017A&A...606A..12H, Cat. J/A+A/606/A12). We
release both the point source selection function and the realistic
source selection function (see Sect. 3.3 of the paper). Note, that the
reported Lyman alpha line fluxes in the galaxy catalogue are corrected
for flux-losses with respect to Herenz et al. (2017A&A...606A..12H 2017A&A...606A..12H);
see Sect. 2.3 of the paper.
Moreover, in this data release we also provide the inverted
log-likelihood function (S=-2lnL) for a Schechter parametrisation
(Schechter, 1976ApJ...203..297S 1976ApJ...203..297S). This function S was obtained with
the maximum likelihood formalism described in Sect. 4.3 of the paper.
As this method does not constrain the normalisation parameter φ*
of the Schechter function, we also release a map of this parameter as
a function of the two other parameters α and L*. A
visualisation of these maps is presented in Figure 12 of our paper.
The selection functions are stored as FITS files (Pence et al.,
2010A&A...524A..42P 2010A&A...524A..42P). The file MW1-24LAELFselfun_ps.fits stores
the point source selection function, while the file
MW1-24LAELFselfun.fits stores the realistic source selection
function. Each FITS file consists of 3 header-data units (HDUs). HDU 1
contains a 2D array of dimension 1000*3681 containing the probability
f (0≤f≤1) that a Lyman alpha emitter at a given flux and wavelength
is contained in the survey catalogue. The first axis of length 1000
corresponds to Lyman alpha flux and the second axis of length 3000
corresponds to wavelength. The translation table between wavelength
index of HDU 1 and wavelength value (in units of Angstrom) is given in
HDU 2 as an 1D array of length 3681. The translation table between
flux index of HDU 1 and flux value F (in units of - logF[erg/s/cm2])
is provided in HDU 2 as an 1D array of length 1000. Section 4 in the
paper describes how this function and the catalogue were used to
construct the non-parametric and parametric determinations of the
Lyman alpha emitter luminosity function.
The values of the inverted log-likelihood map (Equation 22 in the
paper) for the Schechter function parameters alpha and logL* (in
erg/s) are stored as a two-dimensional 401*401 array in the FITS file
MW1-24LAELFsflogLmap.fits. The first axis (NAXIS1) in this FITS
encodes logL*, while the second axis (NAXIS2) encodes the faint-end
slope alpha. The transformation between array coordinates and logL*
and alpha values is linear, with the CRVALi, CRPIXi, and CDELTi
(i=1,2) keywords defining the transformation as described in Wells et
al. (1981A&AS...44..363W 1981A&AS...44..363W). The corresponding normalisation
log(phi*[Mpc-3]) is stored in the FITS file
MW1-24LAELFlogphi_map.fits which follows the same axis conventions
as MW1-24LAELFsflogLmap.fits.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sample.dat 81 237 Lyman alpha emitter galaxy catalogue
list.dat 83 4 List of fits files
fits/* . 4 Individual fits files
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See also:
J/A+A/606/A12 : MUSE-Wide survey: 831 emission line galaxies (Herenz+, 2017)
Byte-by-byte Description of file: sample.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- MW-ID MUSE-Wide object identifier from the
Herenz et al. (2017, Cat. J/A+A/606/A12)
catalogue
11- 19 F9.5 deg RAdeg Right Ascension (J2000)
21- 29 F9.5 deg DEdeg Declination (J2000)
31- 37 F7.5 --- z Redshift of the galaxy (1)
39- 47 F9.5 --- SN Significance of the line detection (2)
49 I1 --- Conf Confidence of the detection (3)
51- 57 F7.5 arcsec RKron Kron radius determined in a synthesized
narrow-band image of Lyman alpha line (3)
59- 69 E11.6 mW/m2 F3Kroncorr Emission line flux extracted in a 3*RKron
radius aperture (in erg/s/cm2) (4)
71- 81 E11.6 mW/m2 e_F3Kroncorr Statistical error on the flux measurement
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Note (1): Redshift of the galaxy, determined from the Lyman alpha line as
described in Sect. 3.3.1 of Herenz et al. (2017A&A...606A..12H 2017A&A...606A..12H).
Note (2): from Herenz et al. 2017A&A...606A..12H 2017A&A...606A..12H).
Note (3): see Sect. 3.2 of the Herenz et al. 2017A&A...606A..12H 2017A&A...606A..12H).
Kron radius (Kron, 1980ApJS...43..305K 1980ApJS...43..305K).
Note (4): corrected for potential flux losses as described in Sect. 2.3 of
the this data-release accompanying paper.
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Nx Number of pixels along X-axis
6- 9 I4 --- Ny Number of pixels along Y-axis
11- 15 I5 Kibyte size Size of FITS file
17- 47 A31 --- FileName Name of FITS file, in subdirectory fits
49- 83 A35 --- Title Title of the FITS file
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Acknowledgements:
Christian Herenz, christian.herenz(at)astro.su.se
(End) Patricia Vannier [CDS] 11-Dec-2018